CHICAGO – Righthander Jared Burton pitched in back-to-back games against the White Sox over the weekend, striking out two batters in each scoreless appearance. It was his first game action in four days, because of postponements and scheduled days off.

“It’s been kind of tough for guys all year,” Burton said. “We haven’t gotten in that regular-season groove yet.”

The results suggest otherwise.

The Twins bullpen has been in lockdown mode in the early season, as roles have been established and newcomers have made a seamless transition into the group. The relievers are coming off two games against the White Sox during which they gave up one run over five innings — a solo homer by Adam Dunn off Josh Roenicke on Sunday.

As the Twins enter a doubleheader against the Marlins on Tuesday — the result of Monday’s game being postponed because of inclement weather, the Twins’ fourth postponement since April 14 — the relievers have posted a 2.15 ERA that was fifth-best in baseball entering Monday. Atlanta led with a 1.22 ERA and was trailed by Texas (1.96), Pittsburgh (2.03), Arizona (2.09) and the Twins. All five teams have records over .500, suggesting the importance of strong relief.

The first few weeks of the season have increased the team’s confidence that if the starters can get through at least six innings and the offense produces as expected, the bullpen will take care of leads. And that will distance the Twins from the past two seasons of 195-loss baseball.

“There are some pretty defined roles down there,” first baseman Justin Morneau said. “You know who is closing [Glen Perkins]. You know who is going to set up [Jared Burton]. You know what lefty is coming in late in situations [Brian Duensing]. Everyone knows what you are doing and when you are doing it. It helps you prepare mentally.”

The Twins entered the season feeling secure about the final two innings. Burton, who battled injuries before last season, posted a 2.18 ERA over 64 games last season and is the main eighth-inning reliever. Perkins saved 16 games last season after taking over the closer’s role for Matt Capps. Perkins, a member of Team USA at the World Baseball Classic last month, is 5-for-5 in save opportunities.

The challenge was building a bridge to the final innings.

The Twins claimed Roenicke off waivers from Colorado, where he posted a 3.25 ERA over 88⅔ innings. Roenicke won’t be asked to pitch as much as he did with the Rockies, sticking to the seventh inning with occasional eighth-inning duties.

Righthander Casey Fien has picked right up from last season, when he posted a 2.06 ERA after being called up from Class AAA Rochester. He entered Sunday’s game in the eighth and got a big strikeout of Chicago’s Alexei Ramirez with a nice breaking ball that was down and on the outside corner.

Duensing will focus on relieving, where he entered the season with a career 3.39 ERA. He can match up with the Prince Fielders and Adam Dunns of the league — but he’s more than a situational lefty.

“He’s not one of those guys you bring in just to get lefties out,” manager Ron Gardenhire said. “He can get lefties and righties out. He has the pitches.”

Righthander Anthony Swarzark is the innings-eater, almost getting a rare four-inning save last Tuesday when he shut down the Angels for 3⅓ innings before giving way to Perkins.

And Rule 5 draft pickup Ryan Pressly — selected from the Red Sox when he was left off Boston’s 40-man roster — is working his way into regular duty. He will likely pitch in the sixth and seventh innings or when the team is trailing, but he can reach around 95 miles per hour with his fastball and the Twins like his breaking pitches, too.

“With Pressly, we can go a lot of different ways,” Gardenhire said. “He’s shown that he can come in those big situations, and he can stretch out.

“I like the fact that we have a lot of options. We have innings out there.”